Scaffolding structures

ABSTRACT

The specification discloses a telescopic scaffolding structure comprising upper and lower rigid booms each of which comprises a three-dimensional framework. Between the booms are struts which telescopically engage with one of the booms so that the booms may be moved vertically relative to one another by telescopic engagement of the struts with the one boom and without dismantling the struts. Jacks are provided for gripping the struts and members of the booms to effect the telescopic movement. The structure may be mounted on ground wheels for maneuverability. Various arrangements of boom framework are described and the booms may be interconnected by articulated or telescopic braces which articulate or telescope during relative movement of the booms.

United States Patent Viandon Apr. 30, 1974 SCAFFOLDING STRUCTURES3,564,803 2/1971 Breeze 52/638 [76] Inventor: Maurice Numa LouisViandon, 151 FOREIGN PATENTS OR APPLICATIONS Avenue de wagram Pans614,171 12/1948 Great Britain 52/637 France 1,274,918 9/1961 FranceZOO/61.39 [22] Filed: Dec. 6 1972 1,279,661 11/1961 France 182/178429,552 5/1935 Great Britain 52/632 [21] Appl. No.: 312,558

Related US, A li ti D t Primary ExaminerHenry C. Sutherland [63]Continuation-impart of Ser. Nos. 799,001, Feb. 13, Awmey, Yates Dowel"1969, abandoned, and Ser. No. 51,314, June 6, 1972, abandmd' 57 ABSTRACT[52] US. Cl 52/638, 52/646, 182/178 The specification discloses atelescopic scaffolding [51] Int. Cl. E04g l/06, E04g l/20, E04g 7/24structure comprising upper and lower rigid booms [58] Field of Search52/111, 112, 632, 646, each of which comprises a three-dimensionalframe- 52/633, 637, 638, 648, 647; 182/152, 178; work. Between the boomsare struts which telescopi- 200/153 N, 61.39 cally engage with one ofthe booms so that the booms may be moved vertically relative to oneanother by [56] References Cited telescopic engagement of the strutswith the one boom UNITED STATES PATENTS and without dismantling thestruts. Jacks are provided 3 354 596 11/196,] schafer 7 "32/152 forgripping the struts and members of the booms to 2237572 4/1941 Maniclsz/ns effect the telescopic movement. The structure may be 1:961:9676/1934 Goransog: 52,632 mounted on ground wheels for maneuverability.Vari- 234Q540 2/1944 Lange I 52/646 ous arrangements of boom frameworkare described 2,431,933 12/1947 Hartmann, 1 2/152 and the booms may beinterconnected by articulated 2,472,423 6/1949 Hawes 52/632 ortelescopic braces which articulate or telescope 2,7 6,299 6/1957Freemanm. 52/111 during relative movement of the booms. 2,874,934 2/1959Dannehl..... 254/29 3,323,271 6/1967 Collins 52/638 4 Claims, 30 DrawingFigures PATH-1TH] APR 3 0 i974 SHEET 03 0F 11 PATENTEQ APR 3 0 ma SHEETOR [1F 11 TEUAPRBO mm SHEET '100F11 SCAFFOLDING STRUCTURES CROSSREFERENCE TO RELATED APPLICATION This application is filed as acontinuation-in-part of a copending application Ser. No. 799,001 filedFeb. 13, 1969, now abandoned, and application Ser. No. 51,314 filed June6, 1972, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The-inventionrelates to a scaffolding structure whose height can be changed and whichis useful for shoring and holding shuttering during construction work.From an extended position in which it holds shuttering the structure maybe telescoped, moved to a different part of the site and thenre-extended to hold shuttering at that part of the site.

2. Description of the Prior Art I-Ieretofore, telescopic scaffoldingstructures have usually comprised a rigid framework usually made up ofdemountable elements and the height of the scaffolding structure hasbeen determined partly by the number of elements included in thestructure and partly by jacks between the lower end of the structure andthe ground and between the upper end of the structure and the shutteringor the like to be supported. The jacks only give a limited range ofadjustment in height and therefore for any large adjustment it has beennecessary to add or remove frame elements. Moreover, if it has beendesired to move the structure from one part of the site to another ithas often been necessary to dismantle it entirely. The object of thepresent invention is to provide a scaffolding structure whose height maybe readily adjusted.

SUMMARY OF THE INVENTION The invention provides a scaffolding structurecomprising: two substantially rigid booms each in the form of athree-dimensional framework and each comprising a plurality of first,mutually parallel members and a plurality of second and bracing membersconnected between adjacent first members to points adjacent the ends ofeach first member; a plurality of neutral parallel struts extendingbetween the booms, the struts and the first members of both booms beingparallel; the first members of one of the booms being tubular and thestruts being telescopically engaged with the tubular first memberswhereby the booms can be moved relative to one another by telescopicmovement of the struts and the first members and means mutually tolocate each strut and the first member withwhich it is telescopicallyengaged.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described indetail by way of example with reference to the accompanying diagrammaticdrawing in which:

FIG. 1 is a side elevation of one form of scaffolding FIG. 5 is a sideelevation similar to FIG. 1 but showing a modification;

FIG. 6 is the side elevation similar to FIG. 1 but showing a furthermodification;

FIGS. 7 to 10 inclusive are detail views of four optional accessoriesfor use with the structures in accordance with the invention;

FIG. 11 is a side elevation of another form of scaffolding structure inaccordance with the invention;

FIG. 12 is a section through part of the scaffolding structure of FIG.11;

FIG. 13 is a detailed view of the first member having integral flangesand showing the connection of the second members;

FIG. 14 is a plan view of FIG. 13;

FIG. 15 is a section through another type of first member having aflange welded thereon;

FIG. 16 is a plan view of the first member of FIG. 15;

FIGS. 17 and 18 are partial sections through further forms of the firstmember;

FIGS. 19 and 20 are partial side elevation and plan respectively of thefirst member having a collar thereon;

FIGS. 21 and 22 are side elevations and plan respectively of part of aboom showing crossed second members;

FIGS. 23 and 24 are plan views of two forms of boom having crossed andparallel second members;

FIGS. 25 and 26 are an elevation and a plan of parts of a boom havingcrossed second members;

FIG. 27 is an elevation of a structure embodying the invention showingdiagrammatically braces between the booms;

FIG. 28 is a detailed view of the structure of FIG. 27 showing anarticulated brace;

FIG. 29 is a plan view of the arrangement shown in FIG. 28; and

FIG. 30 is a detail of the structure shown in FIG. 27 but showing atelescopic brace.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring firstly to FIGS. 1 to4 of the drawings, the scaffolding structure there illustrated comprisesa pair of horizontally extending substantially mutually parallel rigidbooms 10 connected together near their ends in vertically spacedrelationship by vertically disposed telescopically adjustable struts 11.

Each boom 10 comprises a plurality of parallel first members and eachstrut 11 comprises an intermediate assembly 13 in the form of a tube ofsmaller diameter than that of the tubes forming the first members 12 soas to be telescopically slidable within each end thereof.

Each intermediate assembly 13 is formed at equal intervals along thelength thereof with pairs of holes 14 adapted to receive detachably oneof two load pins 15 provided for each intermediate assembly 13, oppositeends of each pin 15 abutting against end flanges 16 which are providedon the opposed ends of the first members 12 of the two booms as well ason the other ends of these members.

Each first member 12 is provided at each end thereof on the inner faceof each flange 1,6, with four flat lugs 17 the planes of which are bothradial and parallel to the central longitudinal axis of each member 12,with the lugs 17 spaced equidistantly around such axis.

The lugs 17 are apertured to receive pins 18 connecting the lugs to theends of second and bracing members 19, 20 extending diagonally indirections respectively across the width of and along the associatedboom and to the next parallel and adjacent member 12.

Thus the first members 12 and the second and bracing members 19, 20constitute each of the two booms 10. These may further embody additionalhorizontal bracing elements 21 which connect together intermediate theirends pairs of diagonally extending mutually crossing members 19, 20.Where the two members 19 and 20 cross one another they are connectedtogether by pins 22 so as with the elements 21 to further increase therigidity of the booms.

In so far as the intermediate assembly 13 of each strut ll telescopeswithin each first member 12, the latter can as shown be formed as acylindrical tube the wall of which is continuous around the tube and atthe same time both ends of each member 12, i.e. including the end nearerto the assembly 13 can, be connected through the lugs 17 to the bracingmembers 19, 20 without interfering with the telescoping of the struts inthe first members 11.

Also in so far as both ends of each first member 12 are secured to thebracing members 19, 20 of each boom, the first members 12 are held veryrigidly against relative lateral movement, i.e., are maintained inalignment with one another, thus ensuring to the maximum extent that thestructure will not fail by bending but only by buckling, i.e., will failonly if loaded substantially in excess of the safe bending load of thefirst members 12 and struts l1.

Adjustment in the overall height of the structure is effected bysuitably selecting the position of one or both load pins in relation tothe pairs of holes in the corresponding end portions of eachintermediate assembly 13 so as to vary the distance by which theintermediate member telescopes within one or both first members 12, aswell as to bring the two booms into close proximity with one another tofacilitate storage or transport of the structure. As shown, eachintermediate assembly 13 is formed in two aligned sections 13a, 13bconnected rigidly but detachably together through integral abuttingflanges 23 secured to one another by removable bolts 24 which bolts maybe also connected to the ends of intermediate bracing bars 25 whichextend horizontally between adjacent mutually parallel struts l 1 so asto reduce the liability of the struts failing by bending.

The construction of each intermediate assembly 13 in two sectionsconnected together by bolts permits if desired of the two sections beingseparated and used as two separate intermediate members 13a, 13b eachtelescoping within a corresponding first member 12 as shown in FIG. 5;the two intermedite members 13a, 13b each receiving telescopicallytherewith one of two intermediate members forming sections 13c, 13drespectively and connected together by flanges 23 as in the case of thesections 13a, 13b in the FIG. 1 construction, to form an intermediateassembly similar to the member 13 of FIG. 1 but of smaller diameter.Each section 130 and 13d is provided with pairs of adjusting holes 14receiving a corresponding load pin 15 the ends of which abut against theflange 23 on the sections 13a 13b. With such an arrangement although themaximum spacing of the two booms 10 may be approximately twice that ofthe construction of FIGS. 1 to 4, insofar as each intermediate membersection 13c, 13d can telescope substantially completely within thesections 13a, 13b respectively and the latter can telescope within theadjacent end member 12, the structure can still be collapsed to aminimum height which is only slightly greater than that of theconstruction of FIGS. 1 to 4.

The arrangement of. FIG. 5 can be further developed to provide as shownin FIG. 6 for a third boom 10a intermediate the two booms 10 alreadymentioned and extending parallel thereto, while still providing the important feature that when fully collapsed the overall height of thestructure is substantially the sum of the overall depth of the severalbooms.

This is achieved by re-arranging the four intermediate member sections13a, 13b, 13c of FIG. 5 in the manner depicted in FIG. 6, as ispermitted by the detachable connection between the sections. Thus thetwo larger diameter sections 13a, 13b are now respectivelytelescopically slidable within a first member 12 of one of the two booms10 and the intermediate boom 10a, with these sections 13c, 13drespectively being telescopically slidable within the sections 13a and13b. The flanges 23 of the sections 13a and 13b are connected to the endflanges 16 on the end members 12 of the other boom 10 and intermediateboom 100. For this purpose the holes 16a of the flanges 16 are disposedin alignment with the bolt receiving holes in the flanges 23 to whichthe flanges are connected by the bolts 24. The versatility of thisarrangement is self evident.

By providing the intermediate boom 10a the resistance to buckling of thestruts of an otherwise similar structure of the same overall height issubstantially doubled.

Referring now to FIGS. 7 to 9 of the drawings, there are here depictedvarious arrangements for effecting adjustment in the overall height ofthe scaffolding structure.

In one arrangement depicted in FIG. 7 an electrically driven screwjackis provided comprising a motor and reduction gear unit 26, which drivesa screw 27 carrying a nut 28 articulated to a first self-clamping fixingdevice 29, applied toa first member 12. The motor and reduction gearunit 26 is fixed to a frame 30 which protects the screw 27 and isarticulated to a second selfclamping device 31 which transmits the forceto one of the intermediate assemblies 13. In order to prevent anyflexing of the screw 27, the latter is suspended from the shaft of themotor and reduction gear unit 26, its bottom end being free or guided ina simple manner; thus, it operates purely in tension whilst the frame30, operates in compression.

Each of these'self clamping devices comprises levers 32, 33 respectivelyand which are respectively hinged at their one ends through pivots 34 tothe nut 28 and frame 30. Each lever 32, 33 carries at two positionsspaced along the length thereof a pair of jaws 35, 36

which respectively engage frictionally but detachably are caused to bindon the members 12, 13 with a force which increases with the loadresisting the extension movement of the strut. Thus the greater the loadapplied by the upper boom to the strut the greater the resistance toslip between the jaws and the members 12, 13 so that provided sufficientpower is supplied by the motor unit 26 the required adjustment in theheight of the structure will be effected.

The arrangement of member engaging jaws depicted in FIG. 7 possesses thefurther advantages that:

a. It permits items to be attached at any desired point on a smoothtube, with any desired angular orientation.

b. The fixing is positive, that is to say no sliding under load ispossible since the clamping load exerted by the jaws rises more steeplythan the sliding force introduced by the load.

Other forms of jack, e.g., hydraulic may be similarly connected to thetwo relatively extensible members of each strut.

As will be readily apparent from FIGS. 1 to 6 the effect of applyingextending force from a jack as above described is necessary to removethe load on the load pins and permit of their removal. When however itis desired to remove a pin without extending the structure by a poweroperated jack this is much more difficult because of the load engagementbetween the pin ends and the part abutting thereon, e.g., flange 16 inFIG. 3.

The foregoing is taken care of with the arrangement depicted in FIG. 8comprising providing between the load pin 15 and flange 16 or if desiredflange 23, a ring 38 rotatably mounted on the strut member having thepin receiving holes 14, i.e., assembly 13 as illustrated, the ring 38carrying a pair of diametrically opposed cams 39, of which only one isillustrated, with the crests of which cams opposite ends of pin 15engage when under load. Rotation of the ring relative to flange 16 or 23is normally prevented by securing peg 40 to retain the parts in theposition shown in FIG. 8.

In operation, the upper boom may be supported by one or moreordinary-screwjacks extending between it and the lower boom. The peg 40is now removed, the ring 38 rotated by striking its arm 41 with a hammerto bring the cams 39 clear of the ends of pin 15 which can now bewithdrawn since the load is taken wholly by the screw jack or jacksmentioned.

If, instead of mechanical or electric jacks, hydraulic jacks suppliedfrom an electrically driven geared pump (or any other kind of pump whosedirection of rotation is fixed), are used, then it is advisable wherethe motor driving the pump is of the three-phase or two-phase type, toprovide a device which makes the motor rotate in the correct direction,however it is connected to the mains. FIG. 9 illustrates a particularlysimple device for this purpose.

On the spindle 42 of the electric motor 26, or upon a shaft drivendirectly or indirectly thereby, there is carried an arm 43, suitablylubricated to prevent any binding. A tension spring 44, one end of whichis fixed to the arm and the other to a fixed point, load the arm 43 intocontact with the drive shaft so that the arm 43, driven by thefrictionforces or the viscosity of the lubricant, tends to rotate in thesame direction as said shaft 42. However, two stops 45 and 46' limit itsrotation. If the motor starts to rotate in the proper direction,indicated by the arrow 47, then the arm comes into contact with the stop45, and nothing further happens. If, however, the motor 26 starts torotate in the wrong direction, then the arm 43 is driven towards thestop 46 but before reaching it, engages the operating member 48 of thechangeover switch 49, which is displaced to reverse the polarity of thecurrent supply circuit 50 of the motor 26 so as to reverse the directionof rotation of the motor and thus ensures proper opera tion. Although inthe embodiment illustrated hereinbefore, the arm 43 is driven byfriction or by the viscosity of the lubricant, other drive media may beemployed, hydraulic, aerodynamic, magnetic and so on. In the latterinstances, the arm 43 is not necessarily carried on the shaft whosedirection of rotation is being monitored, but may be articulated to ashaft rotating in the direction of rotation of the motor, or may forthat matter be replaced by another kind of moving device whose directionof displacement is determined by the direction of rotation of the motor.The changeover switch can equally well be controlled in different ways,for example, in a direct mechanical manner, by electromechanical relays,by hydraulic or magnetic action, through the medium of a photo-electriccell, through a capacitive cell and so forth.

The form of member engaging jaws depicted in FIG. 7 may be applied tothe attachment of a transporting wheel to the structure to facilitateits maneuvering, e. g. on site. For this purpose the two jaws 35, 36already described are similarly articulated to an arm 51 instead of tothe levers 32 33 of FIG. 7. The arm 51 at its free end carries a groundengaging wheel 52. Under the effect of the load carried by the wheel 52,the jaws 35 and 36 clamp around the first member 12, the clamping forcebeing the higher the greater the load, as already described inconnection with FIG. 7.

Referring now to FIGS. 11 and 12, this shows a scaffolding structureindicated generally at 53 comprising an upper boom 54, an intermediateboom 55 and a lower boom 56. The upper boom comprises first members 57which are parallel and which are interconnected by second members 58which brace the first members and are connected between adjacent firstmembers to points adjacent each end of each first member as willhereinafter be described. The boom is a three dimensional structure,there being further first members 57 behind those shown in FIG. 11 andwhich are connected to those shown in FIG. 1 1 by further second members58. The boom can be of any designed size and forms a three dimensionalframework. The second members 58 are in turn braced by members 59. Theintermediate boom comprises first members 60 similar to the members 57and interconnected in the same way by second members 61. In this boomthere are further bracing members 62. The lower boom 56 is identical tothe intermediate boom 55 and comprises first members 63, second members64 and bracing members 65. There are struts 66 between the upper andintermediate booms and struts 67 between the intermediate and lowerbooms. Each strut 66 comprises an outer tube 68 and an inner tube 69. Asshown in FIG. 12, each outer tube 68 is slidable in the first member 60and is guided therein. Each inner tube 69 is slidable in its associatedouter tube 68 in a similar manner. Each inner tube 68 has a series ofspaced apertures 70 and each inner tube has a series of spaced apertures71. Each outer tube 68 is provided at its upper end with a flange 72 andeach inner tube is provided at its upper end with a flange 73.

EAch first member 60 is tubular and is provided at its end with flanges74 and 75. In a similar manner each first member 57 is provided at itsends with flanges 76 and 77. The flanges 77 and 73 of each first member57 and immediately adjacent inner tube 69 are secured together by bolts,not shown.

The boom 54 can be moved vertically relative to the boom 55 bytelescoping movement of the inner tubes 69 in the outer tubes 68 and ofthe outer tubes 68 in the first members 60. Locking pins, not shown, areprovided to enter the apertures 70, and 71 and engage the flanges 74 and72 respectively whereby the spacing between the booms 54 and 55 may bealtered.

A similar arrangement is provided between the booms 55 and 56. Thus thestruts 67 have outer tubes 78 with flanges 79 and inner tubes 80 withflanges 81. The first members 63 have flanges 82 and 83. The adjacentpairs of fingers 75 and 81 are interconnected by bolts, not shown, andthe spacing between the booms 55 and 56 can be adjusted by telescopingmovement of the inner tubes 80 into the outer tubes 78 and of the outertubes 78 into the first members 63.

The flanges at the ends of the first members may be provided in a numberof ways. Thus referring to FIG. 13, this shows a first member 84 whichis secured to second members 85' and the flanges at the ends of thefirst member 84 are indicated at 86 and are formed integrally with themember by forging or other suitable means. It will be seen from FIG. 14that the second members 85 are parallel and are bolted at their ends tospaced holes 87 in the flange 86. It will also be noted from FIGS. 11 to13 that the second members of the various booms extend diagonallybetween the first members of each adjacent pair of first members whenviewed in directions perpendicular to the length of the first members.

FIGS. and 16 show an alternative means of providing flanges at the endsof the first members. In this arrangement a first member such as 87comprises a tube 88 which has its end portions received in preformedflanges 89 which are welded in position. Each flange 89 has a number ofholes 90 equiangularly spaced about its centre.

FIG. 17 shows a still further method of providing a flange 91 on a tube92 forming part of a first member, the flange 91 being welded to asleeve 93 which in turn surrounds and is welded to the end portion ofthe tube 92.

FIG. 18 shows a still further method of securing a flange 94 to a tube95 forming part of a first member. The flange 94 is annular and receivesthe end portion of the tube 95, the end portion being welded at 96 tothe flange.

All the arrangements shown in FIGS. 13 to 18 provide anchorages for theends of the second members such as 85 which cannot become detached fromthe first member clue to a load transverse to the longitudinal axis ofthe first member. Thus in FIGS. 13 and 14 the flange is integral and inthe remaining figures the flange surrounds and is engaged by the endportion of the member so thatit cannot come away therefrom. Even if theend location of the flange fails in the arrangements of FIGS. 15 to 18,this may allow the flange to slide along its associated tube but thiswill not cause any serious dislocation of the structure.

Referring now to FIGS. 19 and 20, this shows how a collar indicatedgenerally at 97 is secured about the end portion of a tube 98 formingpart of the first member. The collar 97 comprises four generallyU-shaped parts 99, 100, 101 and 102 the adjacent limbs of adjacentU-shaped parts being welded together at 103 and also being connected bybolts 104. The collar is located endwise by a ring 105 which is weldedto the tube 98. As will be seen from FIGS. 19 and 20 a second membersuch as 106 may be secured to the collar by one of the bolts 104. Thecollar is prevented from becoming disengaged from the tubes 98 by meansof the bolts 104,

the welds l03.taking little part in the transverse transmission of forcefrom the second member 106 to the tube 38.

Referring now to FIGS. 21 and 22, these show part of a boom indicatedgenerally at 107 and comprising four first members 108,109, 110 and 111provided with flanges at their ends as described above. The firstmembers 109 and 111 are interconnected by second members 112 and 113which as shown in FIG. 22 cross when viewed in directions parallel tothe longitudinal axes of the first members. The second members 112 and113 also extend diagonally between the first members 109 and 111 whenviewed in directions perpendicular to the lengths of the first membersand where the second members 112 and 113 cross they are interconnectedas indicated at 114. It will be seen from the dispositions of theconnections of the ends of the second members 112 and 113 to the flangesat the ends-of the first members 109 and 1 11 that the latter areprevented from rotating about their own axes. In a similar manner, thefirst members 108, 109 are connected by crossed and interconnectedsecond members 115 and first members 108 and 110 are interconnected bycrossed and interconnected second members 116 and the first members 110and 111 are connected by crossed and interconnected second members 117.It will be appreciated that two booms such as shown in FIG. 21 and 22will be interconnected by struts in the manner described in relation toFIGS. 11 and 12.-

Referring now to FIG. 23, this is a plan view of a boom comprising threefirst members 1 18, 119 and arranged at the apices of a triangle. Thefirst members 118 and 119 are interconnected by second members 121 whichare arranged in parallel planes but which extend diagonally as shown inFIG. 21 between the first members when viewed in directionsperpendicular to the length of the first members. In a similar mannerthe first members 118 and 120 are interconnected by second members 122.The first members 119 and 120, however, are connected by crossed secondmembers 123 arranged as described in relation to FIGS. 21 and 22, thesecond members being interconnected thus preventing rotation of thefirst members 119 and 120 about their longitudinal axes. Thedispositions of the second members 121 and 122 also prevent the firstmember 118 rotating about its longitudinal axis.

FIG. 24 shows a plan view of a boom with the first members at thecorners of a parallelogram. The first members are indicated at 124, 125,126 and 127. The first members 124 and 125 are interconnected by secondmembers 128 which lie in parallel planes but are diagonal as describedabove and in a similar manner the first members 126 and 127 areconnected by second members 129. The first members 124 and 126 areinterconnected by crossed and interconnected second members 130 and thefirst members 124 and 125 are connected by crossed and interconnectedsecond members 131, the members being crossed and interconnected asdescribed in relation to FIGS. 21 and 22. It will be seen that the firstmembers are prevented from rotating abouttheir own axes by thedisposition of the various second members.

It will be appreciated that the booms of FIGS. 23 and 24 respectivelywill be interconnected with similar booms by struts in the mannerdescribed with reference to FIGS. 1-1 and 12.

Referring now to FIGS. 25 and 26 .these show a further boom embodyingthe invention. There are four first members 132, 133, 134 and 135, themembers 132, 133 and 134 being arranged at the apices of a triangle'andthe first member 135 being arranged at the mid point of the base of thetriangle. The boom consists of two sets of first members interconnected,the second set corresponding to the members 132 to 135 and beingindicated at 132a to 135a respectively. The flange at the lower end ofeach upper first member is bolted to the flange at the upper end of thecorresponding lower first member. For example the flanges on the members132 and 132a and indicated at 136 and 137 respectively and are boltedtogether.

i The first members of each set are interconnected by second members.The first members 132 and 135 are connected by crossed andinterconnected second members 138, the first members 133 and 135 areconnected by crossed and interconnected second members 139 and the firstmembers 134 and 135' are connected by crossed and interconnected secondmembers 140 all arranged as described in relation to FIGS. 21 and 22.The first members 132 and 134 on the one hand and 133 and 134 on theother are interconnected by second members 141 which are arrangeddiagonally. The various first members are prevented from rotating abouttheir longitudinal axes in the manner described above.

Referring now to FIG. 27 this shows a scaffolding structure embodyingthe invention with a first boom 142 and a second boom 143 and withstruts 144 between the booms. In this construction the struts 144telescope within the first members 145 and 146 of the boom 142. Thefirst members of the boom 142 are braced to the-first members 147 and148 of the boom 143 by braces 149. The braces 149 are either articulatedor telescopic.

Referring to FIGS. 28 and 29 these show telescopic braces between thefirst members 145' and 148. The

brace is indicated generally at 150 and comprises two parts 151 and 152.The parts are articulated at 153 and extra holes are provided in theparts at 154 to allow the axis of articulation to be moved. The part 151has a series of holes 155 in its end portion spaced lengthwise along thepart and the part 152 has a series of holes 156 similarly arranged. Tothe lower flange 157 of the first member 145 there is secured a squarefixing'element 158 having a series of holes 159 in each side spacedapart in a direction perpendicular to the longitudinal axis of themember 145. In a similar manner, the flange 160 at the upper end of thefirst member 148 is provided with a square fixing element 161 which hasin each side a series of holes 162 which are spaced apart in a directiontransverse of the longitudinal axis of the first member.

When the structure is in use, the parts 151 and 152 are locked inposition by a pin 163 which passes through aligned holes in the parts.The ends of the braces are secured to the fixing elements 158 and 161 byengaging bolts in the holes in the fixing elements and in the endportions of the braces. Due to the spacing and arrangement of the holesin these parts the braces can be readily adjusted for different spacingsof the booms. If it is desired to lower the first boom as indicated indotted lines for the first member 145, the pin 163 is removed and thebrace may be articulated as shown in dotted lines without being removedfrom the booms. Thus, if the structure is to be telescoped to be movedto a different position then this can be done by articulatingthe boomswithout having to remove them.

FIG. 29 shows how there may be two braces, one on each side of the firstmembers, the second brace being indicated at 164 and being similar tothe brace 150. In this way, the braces remain clear of the secondmembers during relative movement of the booms.

Referring now to FIG. 30, this shows an arrangement similar to FIG. 28except that the brace between the two booms which is indicated at 165 istelescopic and comprises an outer part 166 and an inner part 167. Theinner part 167 has a series of holes 168 which may be brought intoalignment with any one of a series of holes 169 in the outer part 166-sothat the parts may be fixed in any desired relation. Each part has aplurality of holes at each end to be fixed to the fixing element theends of the first members of the booms. During relative movement of thebooms, telescopic movement between the parts 166 and 167 can take placeif the pins are removed from the aligned holes 168 and 169.

It will be seen that the invention provides a number of modifications ofthe scaffolding structure described in our copending patent applicationNo. 799,00l filed Feb. 13, 1969, and now abandoned.

I claim: 1

1. A transportable scaffolding structure of adjustable overall height,comprising:

at least two substantially rigid booms in superposed relationship, eachin the general form of a right prismatic framework of polygonalplanshape and substantially vertical edges and each comprising I. atleast three tubular upright members extending in non-coplanararrangement along said edges at the apices of said polygonal planshape,each tubular upright member of one of said two booms being insubstantially vertical coaxial alinement with a corresponding tubularupright member of the other of said two booms,

ii..outwardly projecting flanges secured at the ends of said tubularupright members and having thereon a plurality of non-alined attachmentpoints, and

iii. a plurality of intercrossed bracing members extending generally onthe substantially vertical sides of said prismatic framework betweenadjacent tu bular upright members and secured to the flanges thereof atsaid attachment points,

a number of boom spacer struts equal to the number of correspondingcoaxially alined tubular upright members of said two booms and extendinggenerally vertically therebetween in interconnecting extension of theedges of the prismatic framework of said booms, each of said strutsbeing in telescoping engagement with a corresponding tubular uprightmember of at least one of said two booms for extension or retractionrelative thereto, whereby said booms are guidedly slidable in bodilytranslational vertical displacement towards or away from each other tovary said overall height, and

releasable locking means engageable with each telescopable tubularupright member and boom spacer strut assembly to fasten the same againsttelescoping movement, whereby said overall height is adjusted to a fixedvalue.

2. A scaffolding structure as claimed in claim 1, wherein said bracingmembers intercross both when viewed in horizontal directionsperpendicular to the sides of said prismatic framework, and also whenagainst telescopic relative displacement.

1. A transportable scaffolding structure of adjustable overall height,comprising: at least two substantially rigid booms in superposedrelationship, each in the general form of a right prismatic framework ofpolygonal planshape and substantially vertical edges and each comprisingI. at least three tubular upright members extending in noncoplanararrangement along said edges at the apices of said polygonal planshape,each tubular upright member of one of said two booms being insubstantially vertical coaxial alinement with a corresponding tubularupright member of the other of said two booms, ii. outwardly projectingflanges secured at the ends of said tubular upright members and havingthereon a plurality of nonalined attachment points, and iii. a pluralityof intercrossed bracing members extending generally on the substantiallyvertical sides of said prismatic framework between adjacent tubularupright members and secured to the flanges thereof at said attachmentpoints, a number of boom spacer struts equal to the number ofcorresponding coaxially alined tubular upright members of said two boomsand extending generally vertically therebetween in interconnectingextension of the edges of the prismatic framework of said booms, each ofsaid struts being in telescoping engagement with a corresponding tubularupright member of at least one of said two booms for extension orretraction relative thereto, whereby said booms are guidedly slidable inbodily translational vertical displacement towards or away from eachother to vary said overall height, and releasable locking meansengageable with each telescopable tubular upright member and boom spacerstrut assembly to fasten the same against telescoping movement, wherebysaid overall height is adjusted to a fixed value.
 2. A scaffoldingstructure as claimed in claim 1, wherein said bracing members intercrossboth when viewed in horizontal directions perpendicular to the sides ofsaid prismatic framework, and also when viewed in a vertical directionperpendicular to said polygonal planshape.
 3. A scaffolding structure asclaimed in claim 1, wherein said outwardly projecting flanges secured atthe ends of said tubular upright members hAve generally horizontalfaces, and said bracing members have generally horizontal flat endportions securedly applied against said flange faces.
 4. A scaffoldingstructure as claimed in claim 1, wherein each of said boom spacer strutscomprises two mutually telescopable upright sections, and releasablearresting means for locking said upright sections against telescopicrelative displacement.